Faiza Basheer

Bio: Faiza Basheer is an academic researcher from Deakin University. The author has contributed to research in topics: Zebrafish & Medicine. The author has an hindex of 5, co-authored 10 publications receiving 162 citations.

Zebrafish as a model for leukemia and other hematopoietic disorders

Abstract: Zebrafish is an established model for the study of vertebrate development, and is especially amenable for investigating hematopoiesis, where there is strong conservation of key lineages, genes, and developmental processes with humans. Over recent years, zebrafish has been increasingly utilized as a model for a range of human hematopoietic diseases, including malignancies. This review provides an overview of zebrafish hematopoiesis and describes its application as a model of leukemia and other hematopoietic disorders.

Genome editing in zebrafish: a practical overview.

Abstract: Zebrafish is a powerful model for the study of vertebrate development, being amenable to a wide range of genetic and other manipulations to probe the molecular basis of development and its perturbation in disease. Over recent years, genome editing approaches have become increasingly used as an efficient and sophisticated approach to precisely engineer the zebrafish genome, which has further enhanced the utility of this organism. This review provides a practical overview of genome editing and its application in zebrafish research, including alternate strategies for introducing and screening for specific genetic changes.

Conserved IL-2Rγc Signaling Mediates Lymphopoiesis in Zebrafish

Abstract: The IL-2 receptor γ common (IL-2Rγc) chain is the shared subunit of the receptors for the IL-2 family of cytokines, which mediate signaling through JAK3 and various downstream pathways to regulate lymphopoiesis. Inactivating mutations in human IL-2Rγc result in SCID, a primary immunodeficiency characterized by greatly reduced numbers of lymphocytes. This study used bioinformatics, expression analysis, gene ablation, and specific pharmacologic inhibitors to investigate the function of two putative zebrafish IL-2Rγc paralogs, il-2rγc.a and il-2rγc.b, and downstream signaling components during early lymphopoiesis. Expression of il-2rγc.a commenced at 16 h post fertilization (hpf) and rose steadily from 4-6 d postfertilization (dpf) in the developing thymus, with il-2rγc.a expression also confirmed in adult T and B lymphocytes. Transcripts of il-2rγc.b were first observed from 8 hpf, but waned from 16 hpf before reaching maximal expression at 6 dpf, but this was not evident in the thymus. Knockdown of il-2rγc.a, but not il-2rγc.b, substantially reduced embryonic lymphopoiesis without affecting other aspects of hematopoiesis. Specific targeting of zebrafish Jak3 exerted a similar effect on lymphopoiesis, whereas ablation of zebrafish Stat5.1 and pharmacologic inhibition of PI3K and MEK also produced significant but smaller effects. Ablation of il-2rγc.a was further demonstrated to lead to an absence of mature T cells, but not B cells in juvenile fish. These results indicate that conserved IL-2Rγc signaling via JAK3 plays a key role during early zebrafish lymphopoiesis, which can be potentially targeted to generate a zebrafish model of human SCID.

Zebrafish granulocyte colony-stimulating factor receptor maintains neutrophil number and function throughout the life span

Abstract: Granulocyte colony-stimulating factor receptor (G-CSFR), encoded by the CSF3R gene, represents a major regulator of neutrophil production and function in mammals, with inactivating extracellular mutations identified in a cohort of neutropenia patients unresponsive to G-CSF treatment. This study sought to elucidate the role of the zebrafish G-CSFR by generating mutants harboring these inactivating extracellular mutations using genome editing. Zebrafish csf3r mutants possessed significantly decreased numbers of neutrophils from embryonic to adult stages, which were also functionally compromised, did not respond to G-CSF, and displayed enhanced susceptibility to bacterial infection. The study has identified an important role for the zebrafish G-CSFR in maintaining the number and functionality of neutrophils throughout the life span and created a bona fide zebrafish model of nonresponsive neutropenia.

Genetic compensation induced by deleterious mutations but not gene knockdowns

Abstract: Cells sense their environment and adapt to it by fine-tuning their transcriptome. Wired into this network of gene expression control are mechanisms to compensate for gene dosage. The increasing use of reverse genetics in zebrafish, and other model systems, has revealed profound differences between the phenotypes caused by genetic mutations and those caused by gene knockdowns at many loci, an observation previously reported in mouse and Arabidopsis. To identify the reasons underlying the phenotypic differences between mutants and knockdowns, we generated mutations in zebrafish egfl7, an endothelial extracellular matrix gene of therapeutic interest, as well as in vegfaa. Here we show that egfl7 mutants do not show any obvious phenotypes while animals injected with egfl7 morpholino (morphants) exhibit severe vascular defects. We further observe that egfl7 mutants are less sensitive than their wild-type siblings to Egfl7 knockdown, arguing against residual protein function in the mutants or significant off-target effects of the morpholinos when used at a moderate dose. Comparing egfl7 mutant and morphant proteomes and transcriptomes, we identify a set of proteins and genes that are upregulated in mutants but not in morphants. Among them are extracellular matrix genes that can rescue egfl7 morphants, indicating that they could be compensating for the loss of Egfl7 function in the phenotypically wild-type egfl7 mutants. Moreover, egfl7 CRISPR interference, which obstructs transcript elongation and causes severe vascular defects, does not cause the upregulation of these genes. Similarly, vegfaa mutants but not morphants show an upregulation of vegfab. Taken together, these data reveal the activation of a compensatory network to buffer against deleterious mutations, which was not observed after translational or transcriptional knockdown.

The Function of Fish Cytokines

Abstract: What is known about the biological activity of fish cytokines is reviewed. Most of the functional studies performed to date have been in teleost fish, and have focused on the induced effects of cytokine recombinant proteins, or have used loss- and gain-of-function experiments in zebrafish. Such studies begin to tell us about the role of these molecules in the regulation of fish immune responses and whether they are similar or divergent to the well-characterised functions of mammalian cytokines. This knowledge will aid our ability to determine and modulate the pathways leading to protective immunity, to improve fish health in aquaculture.